Fuel injection system venting device



A ril 21, 1959 J. F. 'VERKERKE. 2,883,163-

FUEL INJECTION SYSTEM VENTING DEVICE Filed Aug. 1, 1957 2 Sheets-Sheet 1 INVENTOR.

-April 21, 1959 J.F. VERKERKE 2,883,168

' FUEL INJECTION SYSTEM VEN'IING DEVICE Filed Aug. 1, 1957 2 Sheets-Shet 2 kin 4 0 IN VEN T OR.

AUTO/17V United States Patent FUEL INJECTION SYSTEM VENTI NG DEVICE John F. Verkerke, Oak Park, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application August 1, 1957, Serial No. 675,767 4 Claims. (.Cl. 261 37) The present invention relates to a fuel reservoir venting mechanism for a fuel injection system and more paltioularly represents an improvement in the mechanism shown in copending application Serial No. 648,100 Olson et a1.

It has been found advantageous in the subject type fuel injection system to maintain the fuel reservoir under a slight vacuum to draw ofl fuel vapors and thereby prevent the build-up of vapor pressures therein during idling operation under high ambient temperature operating conditions, particularly as encountered during the; summer months or under conditions of reduced atmospheric pressure. Such high vapor pressures create anun desir-l able pressure on the fuel metering diaphragm tending to shift the latter in a direction increasing the fuel-air ratio causing the engine to eventually stall out due to over-enrichment. The provision of vacuum in the fuel reservoir prevents the vapor pressure build-up during idling under the conditions noted and is the subject. of the aforenoted copending application.

It has been found, however that the vacuum force introduced into the fuel reservoir is not only unnecessary. but actually. detrimental under certain ambient operating conditions. When the fuel vapor pressures are low, as,

during low ambient temperatures, the vacuum force in the reservoir, no longer necessary to neutralize vapor pressure, tends to, shift the metering controhdiaphragm in a direction tending to lean the fuel-air mixture result ing in rough idling operation or stalling.-

The present invention, therefore, provides a thermostatically controlled atmospherio vent in the fuel reser voir which will be opened when the ambient temperatures are relatively low thus eliminating the effect of any vacuum in the reservoir under conditions when it is unnecessary. On the other hand, the atmospheric vent is adapted to be closed when the ambient temperatures reach a level at which the formation of fuel vapors is likely to upset the normal functioning of the fuel metering valve.

The details of the present invention as well as other objects and advantages are set forth in the description which follows:

In the drawings:

Figure l is an elevational view of a fuel injection systern embodying the subject invention;

Figure 2 is a partially sectioned enlargement of that portion of the system embodying the present invention;

Figure 3 is an enlarged view of the thermostatic vent valve; and

Figure 4 is a plan view of the thermostatic vent valve taken along line 4-4 of Figure 3.

The fuel injection system, per se, is shown and descrlbed in copending applications Serial No. 608,797 Olson, filed September 10, 1956 and Serial No. 608,853 Dolza, filed September 10, 1956 now Patent No. 2,843,098 dated July 15, 1958. Therefore, the system will only be described in such detail as is necessary to illustrate the present invention.

An air induction passage is shown at and includes 2,883,168 Patented Apr. 21,. 1 95.9

ice

a venturi portion 12 posteriorly of which is mounted a throttle. valve. 14 adapted to. control, the quantity of air flowing through the system. Thev air induction passage communicates with a plenum chamber 16. from which a series of ram pipes 18 communicate with the individual. cylinders of the. engine. Fuel is supplied to the individual ram, pipes through nozzles 20. The individual fuel nozzles are supplied through passages 24 emanating from a fuel manifold, or distributor 26 which is inturn supplied with fuel through a passage 28 leading from a metering device. indicated generally at 3.0.

The fuel supplying and metering device 30, as shown in, Figure 2, is, mounted, in. ahousing which includes a case. 32, and a cover 34. A conduit 36 is formedin cover 34 and: is supplied with fuel from a low pressure make-up pump, not, shown. A float controlled valve mechanism 38 is also. disposed in cover 34 and communicates with conduit 36 through a passage 40 to which filtered fuel is, supplied in. accordance with the vertical position of the valve member 38 as determined by the positionof a pivoted float actuated arm 42. In the normal manner, as float arm42 israised and, lowered the valve 38- will; shut, off or admit fuel into a fuel. reservoir 44 provided in casing 32.

A constant displacement type pump 50 which is driven a ngine. p ed ismounted n. the fuelr envoir and i adapted; to pump. fuel from the reservoir 44, to a conduit 46 leading generally to a metering chamber 48.

A fuel metering mechanism, is shown generally at 60 and includes a; metering valve member 62 to, which a diaphragm 64 is, connected through arod and. a lever 68; to. mfiter the quantity of fuel supplied by said, valve, to conduit 28.

As best seen in Figur e 2, the upper side of the dia:

phragtn 64 is communieated through, a passage 71] with- Chamber 48I is separated from thefuel, reservoin 44,.

by a perforated partition 51. Inasmuch as wall; 51 is perforated permitting communication between chambers 44 and, 48, it is apparent that the pressure. above the:

fuel, level in. these chambers will; be. the same and for pres nt p rpose he chambers may be. ega e gether as a large reservoir. Eur-thenany.pressureabove: the fuel level in chamber 48 will act on the upper end of the metering valve 62 as well as on the underside of diaphragm 64 through leakage around the control rod 66.

When the engine is idling under conditions of high ambient temperatures or low atmospheric pressures, as would be the latter case when operating in mountainous areas, vapor pressures build up within the chambers 44 and 48 to an extent causing the pressure force to act downwardly on the upper end of the metering valve 62 and upwardly on the diaphragm 64 both of which actions tend to increase the fuel supplied to conduit 28. The consequence of this :added fuel is to over-enrich the idling mixture and thereby cause the engine to stall. This situation has been eliminated in the device of co pending application Serial No. 648,100 Olson et al. by providing a conduit 72 which communicates the one end with fuel reservoir 44 and and at the other end with the fuel induction passage posteriorly of the throttle valve 14. In this way manifold vacuum will draw the fuel vapors out of the chambers 44 and 48 preventing the build-up of undesired pressures therewithin.

As set forth in the last mentioned copending application, full manifold vacuum is not admitted to the reservoir 44 through conduit 72 but rather means, such as an orifice, is provided in the conduit to reduce the vacuum force to a level which will just be sufficient to eliminate the vapor pressure problem encountered.

It has been found, however, under conditions of reduced ambient temperature or increased atmospheric pressure, the fuel vapor pressure in the reservoirs 44 and 48 is of amagnitude to create no fuel metering problem. On the other hand, under these same conditions the introduction of vacuum into reservoir 44 has the eifect of itself disrupting the function of the metering valve 62 by tending to shift the diaphragm 64 downwardly which has the effect of leaning out the fuel-air mixture. To avoid this problem, "an atmospheric vent port 80 is provided in reservoir cover 34. A thermostatically controlled valve 82 of a suit-able bimetallic construction is mounted on the cover 34 and is adapted to coact with the vent 80 to uncover the vent when the ambient temperature is relatively low and to close the vent when the ambient temperatures reach a value at which the vapor pressure within the reservoir 44 again becomes troublesome. In this way, when the ambient conditions are such that vapor pressure within the reservoir 44 presents no problem, atmospheric vent 80 is open bleeding down the vacuum force in chamber 44. When the ambient temperature reaches a level at which the metering valve control is likely to be affected thereby, the thermostatic valve member 82 will close the atmospheric vent and the mechanism will function in the manner described in copending application Serial No. 648,100.

I claim:

1. A fuel injection system for an internal combustion engine comprising an air intake passage, a throttle valve for controlling flow through said passage, a fuel reser-' voir, conduit means communicating the reservoir with the individual cylinders of the engine, valve means disposed in said reservoir for controlling fuel flow to the conduit means, at least one end of said valve being exposed to the pressure in said reservoir above the fuel level, a pump for supplying fuel under pressure to said valve means, a pressure responsive member connected to said valve, a conduit connecting said member to the intake passage for controlling said valve in response to the quantity of air flowing through said passage, said diaphragm being exposed to the pressure in said reservoir above the fuel level, a conduit communicating the intake passage posteriorly of the throttle valve with the fuel reservoir to withdraw fuel vapors from the reservoir, and temperature controlled means for venting said reservoir to the atmosphere when ambient temperatures are below a predetermined value.

2. A fuel injection system for an internal combustion engine comprising an air intake passage, a throttle valve for controlling flow through said passage, a fuel reservoir, conduit means communicating the reservoir with the individual cylinders of the engine, valve means disposed in said reservoir for controlling fuel flow to the conduit means, a pump for supplying fuel under pressure to said valve means, a pressure responsive member connected to said valve, a conduit connecting said member to the intake passage. for controlling said valve in response to the quantity of air flowing through said passage, means utilizing manifold vacuum for neutralizing the fuel vapor pressure in the reservoir, and a temperature responsive device for communicating said reservoir to the atmosphere to eliminate the effect of inanifold vacuum in said reservoir when the ambient temperature is below a predetermined value.

3. A fuel injection system for an internal combustion engine comprising an air intake passage, a throttle valve for controlling flow through said passage, a fuel reservoir, conduit means communicating the reservoir with the individual cylinders of the engine, valve means disposed in said reservoir for controlling fuel flow to the conduit means, a pump for supplying fuel under pressure to said valve means, a pressure responsive member connected to said valve, a conduit connecting said member to the intake passage for controlling said valve in response to the quantity of air flowing through said passage, means utilizing manifold vacuum for neutralizing the fuel vapor pressure in the reservoir during relatively hot ambient operating conditions, a port communicating said reservoir to atmosphere, and a temperature responsive valve adapted to coact with said port to open the reservoir to atmospheric pressure during relatively cool ambient operating conditions.

4. A fuel injection system as set forth in claim 3 in which said temperature responsive valve comprises a bimetallic strip adapted to uncover said port when the ambient temperature is low and close said port when said temperature is high whereby pressure changes in said reservoir will have no effect on the actuation of said fuel control valve means.

References Cited in the file of this patent UNITED STATES PATENTS 2,406,115 Stephan Aug. 20, 1946 

